Please, someone, explain...

In this article, a number of practical jokes played by a nurse are decribed. One of these was her drawing a smiley face on the hernia of an MRSA patient. I am confused.

How does one draw a smiley face on a hernia? What sort of pen do you use? How do you display the smiley face to other people for the full amusing effect? How do you get an MRSA patient to stay still for long enough to draw a smiley face on their hernia?

Any answers in the comments pot, please...